ASTM D6504-2011(2016)e1 9424 Standard Practice for On-Line Determination of Cation Conductivity in High Purity Water《在线检测高纯度水中阳离子导电性的标准实施规程》.pdf
《ASTM D6504-2011(2016)e1 9424 Standard Practice for On-Line Determination of Cation Conductivity in High Purity Water《在线检测高纯度水中阳离子导电性的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM D6504-2011(2016)e1 9424 Standard Practice for On-Line Determination of Cation Conductivity in High Purity Water《在线检测高纯度水中阳离子导电性的标准实施规程》.pdf(6页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D6504 11 (Reapproved 2016)1Standard Practice forOn-Line Determination of Cation Conductivity in High PurityWater1This standard is issued under the fixed designation D6504; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made throughout in February 2016.1. Scope1.1 This practice describes continuous samp
3、le conditioningby hydrogen ion exchange and measurement by electrolyticconductivity. It is commonly known as cation conductivitymeasurement in the power industry although it is actually anindication of anion contamination in high purity water samples.Measurements are typically in a range less than 1
4、 S/cm.1.2 The actual conductivity measurements are made usingTest Method D5391.1.3 This practice does not provide for separate determina-tion of dissolved carbon dioxide. Refer to Test Method D4519.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are m
5、athematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate
6、safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1066 Practice for Sampling SteamD1125 Test Methods for Electrical Conductivity and Resis-tivity of WaterD1129 Terminology Relating to WaterD1193 Specificati
7、on for Reagent WaterD3370 Practices for Sampling Water from Closed ConduitsD3864 Guide for On-Line Monitoring Systems for WaterAnalysisD4519 Test Method for On-Line Determination of Anionsand Carbon Dioxide in High Purity Water by CationExchange and Degassed Cation ConductivityD5391 Test Method for
8、Electrical Conductivity and Resis-tivity of a Flowing High Purity Water SampleD5540 Practice for Flow Control and Temperature Controlfor On-Line Water Sampling and Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, refer to Test Methods D1125, Terminology D1129,and G
9、uide D3864.3.2 Definitions of Terms Specific to This Standard:3.2.1 cation conductivity, nthe parameter obtained byconditioning a sample by passing it through a hydrogen formcation ion exchange resin column and then measuring itselectrolytic conductivity, on-line.3.2.2 specific conductivity, ndirect
10、 electrolytic conductiv-ity measurement of a power plant sample, usually dominatedby treatment chemicals, such as ammonia or amines.4. Summary of Practice4.1 The sample is passed continuously through a smallcation exchange column in the hydrogen form, which ex-changes all cations for H+. In this pro
11、cess, pH adjustingtreatment chemicals, such as ammonia and amines are re-moved.4.2 Measurement is made continuously on the conditionedsample with a process high purity conductivity analyzer/transmitter.4.3 Temperature conditioning of the sample and specializedcompensation of the measurement are used
12、 to minimizetemperature effects on the performance of the ion exchangeresin and the measurement.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power Gener
13、ation and Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved Feb. 15, 2016. Published March 2016. Originallyapproved in 1999. Last previous edition approved in 2011 as D6504 11. DOI:10.1520/D6504-11R16E01.2For referenced ASTM standards, visit the ASTM website, www
14、.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.4 Fe
15、w studies have been published on the performance ofcation conductivity measurement but one collaborative effortprovides some background (1).35. Significance and Use5.1 Cation conductivity provides one of the most sensitiveand dependable on-line means of detecting anionic contamina-tion in the boiler
16、/steam cycle, such as chlorides, sulfates,nitrates, bicarbonates, and organic acids, such as formic andacetic.5.2 High sensitivity is provided by intentionally eliminatingthe pH adjusting treatment chemical(s), for example, ammoniaand amines, from the sample and converting remaining saltcontaminants
17、 into their acid forms which are approximatelythree times as conductive.5.3 Guidelines on cation conductivity limits for variouscycle chemistry and boiler types have been established byEPRI (2-4) and by ASME (5 and 6).5.4 The sample effluent from the cation exchange columnalso may be used, and in so
18、me cases is preferred, for ionchromatography or other anion measurements.6. Interferences6.1 Some weakly ionized cations may not be completelyexchanged by the resin. This will produce positive or negativeerrors in the measurement depending on the sample composi-tion. These errors can reduce sensitiv
19、ity to corrosive contami-nants.6.2 Temperature effects on the cation resin may alter itsequilibrium properties. Control sample temperature within theresin manufacturers temperature limits to obtain consistentresults.6.3 The large temperature effects of high purity conductivitymeasurement must be min
20、imized by sample conditioning andtemperature compensation. Although sample temperature maybe controlled closely, it may be significantly influenced by theambient temperature as it passes through the column, tubingand flow chamber. The temperature coefficient of pure water isnear 5 % of measurement p
21、er C at 25C, which can contributesubstantial errors if not compensated properly. Temperaturecompensation must be appropriate for the unique acidic com-position of cation conductivity samples. Conventional highpurity temperature compensation for neutral mineral contami-nants is not suitable for this
22、application (7 and 8). The user iscautioned that the accuracy of algorithms for cation conduc-tivity compensation may vary widely. The user should deter-mine the applicability and accuracy of the instruments tem-perature compensation in the anticipated temperature range.6.4 Carbon dioxide may be in
23、a sample and will beconverted to carbonic acid and raise cation conductivity. Thisis not strictly an interference; however, carbon dioxide gener-ally is not as corrosive as mineral salts and enters the cycle bydifferent means. Where it is commonly present it may bedesirable to obtain a cation conduc
24、tivity measurement withcarbon dioxide removed (see Test Method D4519.)6.5 Carbon dioxide may also be aspirated as a component ofair, into the sample line through loose fittings in the exchangecolumn, flowmeter, valves, etc. This is not representative of theactual sampling point and produces positive
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